1. Field of the Invention
The present invention relates to a traction device for applying traction to a patient. More particularly, the present invention relates to a traction device that provides a gradual application of the traction force to a patient. Still more particularly, the present invention relates to an electro-mechanical traction device that is light-weight, portable and has feedback and control systems for monitoring and actuating the traction treatment.
2. Description of the Prior Art
As a treatment, physical therapists have found it beneficial to apply traction to patients suffering from muscle and nerve injury. During such treatment, it may often be beneficial to the patient to provide traction on a periodic and repetitive basis. Furthermore, a therapist may wish to apply a greater amount of traction to the patient during any one cycle to achieve better results faster than would be the case if only static force were used. Even better therapeutic results can be obtained by providing a relatively "soft" traction force on the patient (i.e., a traction force that does not reach its maximum value instantaneously but which gradually increases to the maximum value).
Devices for applying traction force to a patient are known in the industry. For example, static weight systems for applying traction forces to patients are known, such as is shown and described in U.S. Pat. No. 4,508,109 to Saunders. However, the traction force applied by the device of Saunders is constant. Furthermore, the device is neither relatively light-weight nor portable.
Devices for applying traction forces periodically to a patient are also known in the industry. Such a device, for example, is shown and described in U.S. Pat. No. 3,786,803 to Petulla et al. The apparatus of the Petulla et al. patent utilizes a direct drive traction device having a motor driven spool for spooling a cable connected to a harness attached to a patient. A controller is provided to activate the motor on a periodic basis to provide the traction force.
Also known in the industry are pneumatic traction devices, such a device is shown in U.S. Pat. No. 5,181,904 to Cook et al. The traction device of Cook et al. purports to provide a relatively "soft" traction force to patients. The apparatus of Cook et al. utilizes a carriage traction device attached to the shaft of a pneumatic cylinder powered by a motor driven compressor. The compressor required for the use of pneumatics adds weight and bulk to the device, reducing the portability of the device.
Thus, it would be advantageous to provide a traction device which is relatively light-weight and, therefore, portable. Such a device should further provide a softer traction force to the human body with more tolerance in the traction process than has otherwise been available in the industry.